BreakQuest from Nurium Games is an excellent Breakout clone that introduces many new gameplay elements, most notably in it's level design. Each stage is built around a certain theme and offers it's own set of challenges for you to overcome. Expect to encounter bricks in all sorts of variety, shape and sizes.

Gravity plays an important role in the game. You can use it to influence the trajectory of the ball, and it comes in handy when you're left with only a few bricks to bust. There are numerous power-ups that'll grant you missiles, multi-balls, mines and guns, among other things.